1. Field of the Invention
The present invention relates to a reinforcing brace. More particularly, the present invention relates to an improvement of the reinforcing brace for reinforcing a floor panel, which is installed to an undersurface of the floor panel of a vehicle so as to extend in a vehicle width direction.
2. Discussion of Related Art
Conventionally, various safety standards for vehicles such as motorcars are set to protect occupants from injuries resulting from impact collisions. Such safety standards for vehicle and the like are becoming more stringent year by year. A new safety standard to protect occupants from injuries resulting from side impact collisions (hereinafter, referred to as a side impact safety standard) was introduced in a few years ago. The side impact safety standard requires not only a side panel such as a door panel but also a floor panel providing a floor of vehicle to meet the standard. Thus, in recent years, as one option to meet the side impact safety standard required to the floor panel, a longitudinal reinforcing brace for improving the strength of the floor panel has been increasingly installed to the floor panel so as to extend in a vehicle width direction.
As such a reinforcing brace or reinforcement device for use in a floor panel, there are known a reinforcing brace formed of a metal pipe (see, JP-A-2008-279951) and a reinforcing brace composed of a press-formed product having an angular U-shaped cross sectional shape which is made by a longitudinal plate formed of a super high tensile strength steel through hot press, for example. However, the following problems are inherent in the conventional reinforcing braces formed of the pipe and the press-formed product having an angular U-shaped cross sectional shape.
Specifically, in the reinforcing brace formed of a pipe, a plurality of insertion holes for fastener members such as bolts, which allow the reinforcing brace to be installed to a floor panel, are positioned in installation sections located at both end sides in a longitudinal direction (axial direction) of the reinforcing brace. However, the width of the installation section of such reinforcing brace is inevitably small, because the installation sections of the reinforcing brace are formed by pressing both end side portions in a longitudinal direction of the pipe so as to have a flat shape. In other words, the width of the installation section is limited by the outside diameter of the pipe. Therefore, it is difficult to freely set a position and interval of the plurality of insertion holes in the installation section of such a small width. Consequently, it is also difficult to freely set a position of the fastener members, which are inserted into the insertion holes positioned in the installation section, when installing the reinforcing brace beneath the floor panel. Meanwhile, the floor panel to which the reinforcing brace is installed generally has a lot of concave and convex portions, and various members and parts are installed thereto. For this reason, when the reinforcing brace formed of a pipe is used as a reinforcing brace for a floor panel, installation of the fastener members, which are inserted into the insertion holes of the installation section, to the floor panel by the fastener members poses difficulties, because there is few flat area in the floor panel and it is difficult to set a position of the reinforcing brace so as not to be in contact with the other members and parts installed to the floor panel.
Even in such a reinforcing brace formed of a pipe, if flat brackets of large width are joined by welding, for example, to both end portions in a longitudinal direction of the pipe to form installation sections, position and arrangement intervals of a plurality of insertion holes positioned in the installation section can be set freely. However, due to the welding of the brackets, the number of facilities and processes in the production of the reinforcing brace will increase. Further, the number of parts for the reinforcing brace will increase because of the employment of the bracket, which is an independent member from the pipe. Consequently, deterioration in productivity of the reinforcing brace and an increase in the production cost thereof will be inevitably caused.
Meanwhile, the reinforcing brace formed of a press-formed product having an angular U-shaped cross sectional shape has a configuration in which a side wall is vertically provided on each side in a width direction of a longitudinal flat portion. Therefore, in such reinforcing brace, the width of the flat installation sections made of the end portions in a longitudinal direction of the steel plate can be set freely by changing a width of the steel plate, which is a material of the reinforcing brace, or by changing a height of the side wall which is formed by press working against the steel plate, for example. Thus, the position and intervals of the plurality of the insertion holes in the installation section can be freely set. However, torsional rigidity of the reinforcing brace formed of the press-formed product decrease more as the width of the flat portion become bigger. Accordingly, it is difficult to secure the same torsional rigidity as the reinforcing brace formed of a pipe. In addition, when such a reinforcing brace is installed to the undersurface of the floor panel so as to extend in a vehicle width direction, the side walls vertically provided on the both end sides in the width direction of the flat portions are arranged so as to protrude from the floor panel in a vertically downward direction. Due to this arrangement, air resistance under the vehicle body while driving is increased and aerodynamic performance is deteriorated.